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EMISSIONS GAP REPORT 2018 – THE EMISSIONS GAP
3.5.1 Limiting future reliance on carbon dioxide removal
22–53 percent below current NDC levels in 2030, which would align emission levels with below 2°C and 1.5°C pathways, would substantially alleviate the trade-off between disruptive emission reduction requirements post-2030 and potentially unattainably and unsustainably high CDR deployment. The IPCC Special Report indicates that the CDR requirements to compensate for an overshoot of 0.2°C or larger during this century might not be achievable (IPCC, 2018). Furthermore, optimal 2030 GHG emission levels depend strongly on the availability of CDR: below 1.8°C and below 1.5°C pathways with limited CDR have 7–12 GtCO2
Mitigation scenarios that stabilize global warming to well below 2°C or 1.5°C differ widely in their use of CDR (Rogelj et al., 2018b), which is associated with several environmental and social sustainability risks (Smith et al., 2016; Minx et al., 2018). CDR of some form will likely be required for these warming limits, especially the 1.5°C goal, though its extent may vary (Rogelj et al., 2015; Luderer et al., 2018). A recent study (Strefler et al., 2018) shows that strengthened action in the near future can significantly decrease CDR requirements for the remainder of the century. Reducing CO2
emissions by e less 2030 GHG emissions
than corresponding pathways with a full technology portfolio. The six 1.5°C pathways available from the literature that limit the availability of biomass with carbon capture and storage technologies (Bauer et al., 2018; Bertram et al., 2018; Grubler et al., 2018; Holz et al., 2018; Kriegler et al., 2018; van Vuuren et al., 2018) all have GHG emission levels of at most 25 GtCO2
e in 2030. 3.5.2 Achieving sustainability
Numerous interactions and potential synergies and trade-offs between climate change mitigation and other sustainability objectives are highlighted in the recent literature (von Stechow et al., 2015; 2016; Jakob and Steckel, 2016; UNEP, 2016; Bertram et al., 2018; McCollum et al., 2018). Broad societal choices and developments regarding lifestyles and socioeconomics will determine the feasibility and effort required to simultaneously achieve the Paris Agreement’s objectives and the Sustainable Development Goals (Rogelj et al., 2018a). The literature also shows that stronger near-term emission reductions have the potential to increase mitigation co-benefits in both the coming decade and later in the century, for example, through reduced air pollution, lower water demand and decreased dependence on bioenergy (Bertram et al., 2018; IPCC, 2018). For instance, Rao et al. (2016) show that combining deep decarbonization with stringent air pollution control policies can decrease the share of global population exposed to high particulate matter concentrations from 21 percent to 3 percent in 2050.
Paris Agreement targets. In addition, dedicated policies for differentiated carbon pricing or energy efficiency regulation have been identified to effectively mitigate potential adverse side effects, such as exceedingly large land requirements for bioenergy (Bertram et al., 2018) or impacts of climate policies on food and energy prices (Fujimori et al., 2018). Grubler et al. (2018) have shown that strong efforts towards improving energy efficiency lowers near-term GHG emissions, increases sustainability co-benefits and could keep the 1.5°C limit within reach with much lower CDR levels.
Markandya et al. (2018) estimate that air pollution- related mortality during the 2020–2050 period can be reduced by around one quarter compared with business as usual if CO2
emission reductions are in line with the
3.5.3 Avoiding lock-in of carbon-intensive infrastructure
coal-fired power plants currently under construction go into operation and run until the end of their technical lifetime, the coal emissions commitment will increase by another 150 GtCO2
Sociotechnical systems in general and energy systems in particular are characterized by inertia and path dependency due to long-lived capital stocks with slow turnover, infrastructure requirements, learning by doing and cultural practices. As noted in previous Emissions Gap Reports, these inertias give rise to the notion of carbon lock-in, which is large-scale committed emissions resulting from existing infrastructures (see also Unruh, 2000; Davis et al., 2010). The scenario literature clearly demonstrates that weak near-term climate policy ambition increases the long-term emissions commitment from fossil-based infrastructures, decreases the economic mitigation potential (Bertram et al., 2015; Kriegler et al., 2015; Luderer et al., 2018) and greatly increases the risk of stranded assets when switching to a 2°C-consistent mitigation pathway (Johnson et al., 2015; ; Riahi et al., 2015; Luderer et al., 2016). Attempting to hold the below 2°C limit from the 2030 emission levels implied by the NDCs would require rapid emission reductions after 2030, resulting in stranded assets of several hundred billion US$ from coal power alone (Johnson et al., 2015). Coal-based power is the most important cause of carbon lock-in today (Davis et al., 2010; Bertram et al., 2015; UNEP, 2017), with all plants currently in operation committing the world to around 190 GtCO2
(UNEP, 2017; Edenhofer et al., 2018). If all , jeopardizing the achievement of NDC
emission reduction targets and the Paris Agreement’s long-term warming limits (Edenhofer et al., 2018). Strengthening 2030 efforts beyond the NDCs will not only reduce near-term emissions, but also crucially reduce carbon lock-in, paving the way for the deep emission reductions required in the longer term.
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